Bandwidth Calculator

File size and connection speed — how long the transfer will actually take.

GB
Mbps

Internet speeds are sold in megabits per second (Mbps), but file sizes are shown in megabytes/gigabytes (MB/GB) — 1 byte = 8 bits, which is why a "100 Mbps" connection downloads at roughly 12.5 MB/s, not 100 MB/s.

Estimated download time
6m 49s
Effective speed
12.50 MB/s

Real-world transfer speeds typically run somewhat below the rated connection speed due to network overhead, server-side limits, and other traffic sharing the connection.

A worked example

A 5 GB file on a 100 Mbps connection takes about 6 minutes 50 seconds at full theoretical speed.

Frequently asked questions

Why does my 100 Mbps connection not download at 100 MB/s?

Internet speeds are measured in megabits per second, while file sizes are shown in megabytes — since there are 8 bits in a byte, a 100 Mbps connection tops out at about 12.5 MB/s, not 100 MB/s. It's one of the most common points of confusion in networking.

Why might my actual download be slower than this estimate?

This calculates a theoretical maximum based purely on your connection's rated speed — actual throughput is often lower due to network congestion, server-side bandwidth limits, Wi-Fi signal quality, or other devices sharing the same connection.